Getter



Dec. lo, me. l R SPENCER K www GE'TTER Filed Deo. s, 1941 Patented Dec.10, 1946 'U N ITED STATES iig-.T EN T '0 FF ICE GETTER ApplicationDecember 3, 1941, Serial No. 421,403

(Cl. Z50-2.27.5)

4 Claims.

r-I'his invention relates to a getter arrangement and method forintroducing a getter, particularly in connection with that ,type ofdischarge tube which is made with a metal envelope.

A number of discharge tubes are made with their outer envelope rof metalthrough which lead-in Vconductors .are `introduced by means ofinsulating seals. In such tubes difficulties lhave been encountered invaporizing Vgetter materials due to the `fact that the .metal envelopeelectrically shields the interior of. the tube, and thus prevents theusual .induction heating for the purposes of vaporizing the getter.Various other methods of heating the vgetter have been attempted, -butheretofore yeach such attempt has encountered serious difficulties.

An object of this invention is yto devise 'an arrangement whereby .agetter may be vaporized into a metal envelope by induction heating.

Another object is to accomplish `the foregoing without producingundesired heating of anyof the glass-to-metal'seals ofthe metalenvelope.

A further object is `to accomplish the heating of the getterin a simpleand effective and reliable manner.

The foregoing and other objects of this invention will be bestunderstood from the following description of an lexempliiicationthereof, reference being had to the accompanying drawing, wherein:

Fig. 1 is a side view of a metal envelope tube, such as a magnetron,incorporating certain features of my invention; and

Fig. 2 is a cross-section of the getter arm taken along line 2--2 ofFig. l, and showing the auxiliary elements which are associatedtherewith during vaporization of the getter.

The tube shown in Fig. 1 consists of a hollow metal envelope I which maybe made of a highlyconductive material, such as copper. For example, theenvelope I may be part of a magnetron. Such a magnetron is provided witha number of metallic pipes 2 and 3 hermetically sealed into the tubewalls and through which lead-in conductors are introduced into the tube.For example, the pipe 2 has sealed to its outer end a glass chamber 4through the outer end of which is sealed a leadin conductor 5 which mayextend to one of the electrodes within the tube, such as the cathode.

In the same way a lead-in conductor 6 which, for example, may be thehigh frequency lead from the tube, is sealed through the end of the pipe3, which may constitute a lead extending from the the envelope I,serving in this instance as the anode of the magnetron. The pipe 3 maylikerent.

walls of the cup I0, and generate sufficient heatl wise carry .aconductive pipe 'I which .surrounds the conductor 6 and forms therewitha concentric high frequency line. The envelope I .may be provided withone or `more additional lpipes not shown, through which lead-inconductors sealed through a glass seal at the outer end of said lpipesextend.

In addition to the above construction,there is provided a pipe or tube 8of conductive material, such as copper, hermetically sealed in the wallof the envelope. The pipe `8 has sealed to the outer end thereof a glassenvelope 9. The interior of the envelope 9 as well as that of the pipe 8communicate with the interior of the envelope I. Within the envelope '9is supported a metallic cup III, at the bottom of which is contained agetter material II. This getter material `may be, for example, an easilyvaporizable material, such as barium, or a reaction mixture, such asbarium oxide and aluminum. "The ygetter material vII is maintainedwithin 'the cup I0 by a perforated metallic insert I2, which may beretained in place within the cup I0 by being welded thereto. Theperforations in "the insert I2 Ypermit vaporized getter 'material toescape into the envelope 9. The cup "IIJ may be Asupported fby means 0f`an `open spiral spring I3, one lend of which is lwelded 'to the AcupVIIl and vthe rother end of which is of 'sufficient diameter to firmlyengage the inner walls of the envelope 9, thus retaining the cup Illrmly in place at substantially the center of said envelope 9. It will benoted that the cup Ill has its open end facing the back of the envelope9 so as to avoid the blowing of z particles liberated within the cup I0into the interior of the main envelope through the pipe 8.

After the tube has been exhausted and freed of occluded gases in theusual manner, the getter material I I is liberated by surrounding theglass envelope 9 with a coil I4 which is adapted to be fed withrelatively high frequency induction heating current from a pair oflead-in conductors I5. These conductors I5 are adapted to be connectedto a suitable source of high frequency cur- In this way currents areinduced in the to raise the material I I to vaporizing or reactiontemperature at which the getter material is vaporized and deposited onthe walls of the envelope 9 to accomplish the usual residual gascleanup. Thus it will be seen that the getter material is readilyvaporized by induction heating without substantial interference withsuch action due to the fact that the discharge device involved possessesa metallic envelope.

When the coil I 4 is placed around the cup I0, it likewise approachesthei seal I6 between the pipe 8 and the glass envelope 9 so closelyVthat in absence of some protective means, heat would be generated withinthe walls of the pipe 8 to such an eXtent as to injure said seal. I havefound that this injurious heating maybe avoided without substantialinterference with the heating ofY the getter by surrounding the seal I 6with a relatively heavy ring I'I of a highly-conductive material, suchas copper. The ring I1 may be supported in proper position, for example,by a standard I8. The copper ring I1 has such a low resistance that anycurrents which are generated in it by means of the coil I4 do notliberate a suflicient amount of heat to substantially raise thetemperature of said ring I'I. .At the same time this actioneffectivelyprotects and shields the seal IB against the generation 'ofheat adjacent said seal. In this way I have been able to effectivelyvaporize theV getter material II without any danger of injuring the sealI6.

Of course it is to be understood Athat this invention is not limited tothe particular details as described above as many equivalents willsuggest themselves to those skilled in the art. For example, thearrangement which I have shown lends Y ductive material to preventundesired heating ofk i Y' itself to other types of heating of gettermaterials Y ing with the interior of said envelope, and a va-Y porizablematerial contained within said space adjacent the seal between saidglass and conducting envelopes, said method comprising subjecting saidvaporizable material to a varying magnetic iield` to produce inductionheating thereof,.and surrounding said seal with a body of a good consaidseal. Y

2. The method of introducing a vaporizable material into a dischargedevice comprising an envelope of a conducting material, a glass envelopesealed to said envelope projecting exteriorly of said envelope andenclosing a space communicating with the interior of said envelope, anda, vaporizable material contained within said space adjacent the sealbetween said glass and conducting envelopes, said method comprisingsub-- jecting said vaporizable `material to a varying magnetic field toproduce induction heating there-r of, and surrounding said seal with arelatively massive ring of a good conductive material to preventundesired heating of said seal.

3. `The method of introducing a vaporizable material into a dischargedevice comprising an envelope of a conducting material, a hollowconducting tube communicating with the interior of said envelope andsealed -to the wall thereof,V aglass envelope sealed to the outer end ofsaid tube and enclosing a space communicating with the interiorof saidtube, and a vaporizable material contained within said space adjacentthe vseal between said glassl envelope and said tube, said methodcomprising subjecting Vsaid vaporizable materialto a varying magneticiield to produce induction heat`` i ing thereof, and surrounding saidseal with a body of a 'good conductive material toY preventvundesiredheating of said seal.' i

- 4. The method of introducing a varnorizablema#V terial into adischarge device comprising an enve' lope of a conducting material, ahollow conduct-I ingY tube communicating with thev interior "of 'saidenvelope and sealed to the wall thereof, a glass envelope sealed totheouter end of said tube and enclosing a space communicating with theinterior of said tube, and a vaporizable materialcontained within saidspace adjacent the seal between saidVv glass envelope and said tube,said method com# prising subjecting said vaporizablematerial to"avarying magnetic eld to produce induction heating thereof, andsurrounding said seal lwith a relatively massive ring of a goodconductive materialA to prevent undesired heating of said sealt yPERCY nSPENCER. Y'

